1. Field of the Invention
The present invention relates to a uniformity inspection system for inspecting the uniformity characteristics of an assembled tire and correcting and re-inspecting the uniformity characteristics as required.
2. Description of the Prior Art
A product tire which has gone through a curing step and a finishing step is shipped after product inspections such as appearance and shape inspections and uniformity measurement are made.
As for the measurement of the uniformity of a tire, a tire 12 assembled with a rim is pressed against a rotating drum 11 corresponding to a road under load and turned while the axial distance between the tire 12 and the drum 11 is fixed as shown in FIG. 3(a) to measure a load variant (RFV), a longitudinal force variant (LFV) and a transverse force variant (TFV) as shown in FIG. 13(a), and displacement gauges 13a and 13b are pressed against the tread portion 12a and the side portion 12b of a rotating tire 12 to measure the size nonuniformity in the longitudinal direction (RR) and size nonuniformity in the transverse direction (LR) of the above tire 12 as shown in FIGS. 3(b) and 3(c).
When the above measured uniformity characteristics are within specified values, the tire is accepted and when they are outside the specified values, the assembly state of the tire with the rim is corrected, a size nonuniform portion or a projecting portion which causes the vibration of the tire is shaved off with a correction device such as a buff machine and then the uniformity characteristics of the corrected tire are re-measured.
FIG. 4 shows the outline of a conventional uniformity inspection line. The tires 12 which are sorted and distributed after an appearance inspection is made while they are carried on the conveyor 21C of an automatic sorting line 21 are supplied to a uniformity inspection line 22 having a plurality of uniformity inspection machines (to be referred to as “UF machines” hereinafter) 22M so as to measure their uniformity characteristics with the UF machines 22M.
The above UF machine 22M has a uniformity measuring function and a uniformity characteristics correction function. When the uniformity characteristics of the tire measured with the UF machine 22M are within specified values, the tire is carried to the subsequent step by the conveyor 23C of a conveyor line 23 as an accepted product. When the uniformity characteristics of the tire are outside the specified values, after the above tire is corrected by an unshown correction machine such as a buff machine provided in the UF machine 22M, the uniformity characteristics of the corrected tire are re-measured. When the uniformity characteristics of the above corrected tire are within the specified values after the re-measurement, the tire is supplied to the subsequent step as an accepted product and when the uniformity characteristics are outside the specified values again, the tire is supplied to the collection conveyor 24C of a collection line 24 as an unaccepted product.
However, as for the number of the above UF machines 22M, only the minimum required number of UF machines 22 which differs according to such conditions as the number of tires to be produced, the number of different sizes of tires to be produced and the estimated number of tires whose uniformity characteristics are to be corrected are installed. Therefore, when the number of tires whose uniformity characteristics are to be corrected greatly changes, an automatic line may not function properly. That is, the uniformity measurement time of the above UF machine 22M is almost fixed for the tires of each size but the uniformity characteristics correction time is several times longer than the above uniformity measurement time though it differs according to the size and uniformity characteristic values of the tire. Therefore, when the number of tires whose uniformity characteristics are to be corrected increases, the number of tires which can be processed by the UF machine 22M is reduced. Consequently, as the capacity of the automatic line is reduced by the overflow of the tires 12 to the automatic sorting line 21, the tires 12 on the above automatic sorting line 21 must be manually taken out and carried to a storage site temporarily so that the automatic line can function properly. When the load of the automatic line is reduced, the extra work of returning the above stored tires 12 to the automatic line is necessary.
It is an object of the present invention which has been made in view of the above problem of the prior art to provide a tire uniformity inspection system capable of carrying out uniformity inspection efficiently even when the number of tires whose uniformity characteristics are to be corrected changes.